const Transform = require('stream').Transform;

class LastNewline extends Transform {
  constructor() {
    super();
    this.lastByte = false;
  }

  _transform(chunk, encoding, done) {
    if (chunk.length) {
      this.lastByte = chunk[chunk.length - 1];
    }

    this.push(chunk);
    done();
  }

  _flush(done) {
    if (this.lastByte === 0x0a) {
      return done();
    }
    if (this.lastByte === 0x0d) {
      this.push(Buffer.from('\n'));
      return done();
    }
    this.push(Buffer.from('\r\n'));
    return done();
  }
}

module.exports = LastNewline;
